1. Field of the Invention
The invention relates to a smart card. In such cards, a module including the semiconductor chip is permanently fixed in a cavity in the card. The card itself can be molded from a plastic as a single piece. Preferably, the plastic is molded so as to form the cavity for the semiconductor chip. Alternatively, the card can consist of multiple layers connected to one another by lamination. In this case, the cavity is cut into the card.
2. Description of the Prior Art
A module to be implanted in a smart card of this type is described in German Reference DE 37 23 547. The module is fixed in the cavity of the card by means of a heat adhesive layer. To activate the heat adhesive layer and establish the adhesive connection, the layer must be heated at least briefly to relatively high temperatures, in some cases up to 150.degree. C. To this end, the module is implanted in the card by means of a heat punch. It is disadvantageous, first of all, that the card experiences plastic deformation in the cavity region due to the heat. This detracts from the optical impression of the card surfaces, which bear high-quality printing. Secondly, it is difficult and expensive to find and duplicate the optimal parameters for the implantation process (temperature of heat punch, duration of heat, geometry of punch, etc.). Furthermore, a special problem arises in processing semiconductor chips of various sizes, because the heat absorbed by the chips and the heat conducted to the heat adhesive layer depends on the size of the semiconductor chip. Incorrectly set parameters thus result in poor adhesion. Under certain circumstances, the adhesion is so inadequate that the module can be removed from the card very easily. In addition, overheating the sensitive semiconductor module can impair its function.
Furthermore, it is known from German reference DE 42 29 639 to fix modules of this type in cards by means of instant adhesives based on cyanoacrylate. However, since such adhesives take only seconds to harden, they cannot be applied to one or both of the surfaces to be connected until immediately before the module and the card are put together. This requires an additional process step linked directly to the implantation step in terms of time (and thus in terms of space as well). When instant adhesives are used, it is therefore not possible to provide mass-produced modules with adhesive layers and then store them for days or weeks prior to the actual implantation process.